OSX Disk Defragmentation

[jardo]

Refresh my memory, does/should one defragment a xServe RAID (768gb & 2.2TB)??? If yes, what do you use?

[mattbeals]

Nope. The data is "fragmented" across the various discs. Totally un-necessary on RAID 3,5, or 6 volumes. Stripes, mirrors and mirrored stripes "possibly". But again not really necessary. Single disc volumes, yes it's helpful. RAID's, don't bother.

[jardo]

Thanks. So what do you use on single disks? I thought at some time I read that HFS+ formatted disks do not need to be defragmented? True?

[PrePress Guru]

I use a product called iDefrag. Its pretty easy to use but if you want to fully defrag your startup disk, you will need to boot off of a different volume.

-Ian

[maxon]

Any disk (single drive as said before) requires defrag once in a while depending on usage, regardless of its system file / format.
HFS+ uses some adaptive algorithms to dinamically group together the most recent used bits of data in the catalog b-tree and extents, but in most cases defrag is beneficial if the disk has been used heavily.
I use IDefrag as well (bootable DVD) to carry out maintenance when required.